Sound card directly to amps SQ?

I'm in the planning/component gathering process of my CarPC...

I've got a Sound Blaster 5.1 PCI sound card and a Rockford Fosgate 800a4 for front and rear channels, an RF 800a2 for my subs and an RF 75a2 for center (only using one channel) . I am concerned about the voltage level coming from my sound card to my amps and if it will be enough. I'm looking for SQ and true surround sound. Will this:
produce good SQ for me? Or will I need a signal processor or maybe even a line driver... Other options? My sound card is KX driver compatible and I plan on using the drivers and other features to adjust my sound field...

Depending on which sb card you're using, you should be ok without the line driver. Actually any should be ok. Only thing you'll gain with a line driver is a lower noise floor. You'll notice that when you crank up the master volume on your PC, there will be more white noise present, which is inaudible during loud music play anyway. This is eliminated with a line driver since the volume on the pc can be always set much lower.

I do want surround sound for watching DVD's for my passengers on long trips. We frequently drive for 2+ hours for snowmobile trips. As for music playback, stereo is just fine. My MAIN question is will my sound card produce enough voltage to my amps without the need for a line driver to up the voltage? I guess I will just get a line driver to clean up the signal...

I'm running a setup like this, VIA SP13000 hooked directly to 2x 4CH amps. Amp1 is connected to L/R Front+SUB and Amp2 is connected to L/R Rear+SUB. This is a 4.1 setup with a single SUB with dual voice coils. The VIA is doing all signal processing including crossover for the sub. This setup works flawlessly for me, but I only have about 30cm between the amps and the computers => short cables => minimal noise pickup from car ignition etc.

A computer sound output is about 0.7V and headunits 2V, even 5V i believe (numbers not verified). A higher peak-peak voltage equals lower noise floor and is important when you do long cableruns in a car (headunit => trunk). When running amps directly off the PC it's important to keep the signal cables to a minimum since you'll be running the amps with a higher gain (more noise) than with a 2V source. Every car amp should be able to run at full potensial off a 0.7V source, my gain on the amps is about 70% letting me play at full capacity when the PC volume is 100%. But i guess this is up to the manufacturer, if they only intened to run the amp on high output sources, you might end up not having "enough" gain on the amp to play at full capacity - but I don't know if such an amp even exists, my guess is that is that every amp should work fine.

Bottom line; keep your signalpath short, if you can't move the computer close to the amps, run a USB cable from the PC to the amps and run the amps off a USB soundcard in close proximity. You might also be able to find a soundcard with a high output, ASUS Xonar D2 claims to be capable of 2Vrms (5.65Vp-p).

IceSocket: Thanks for the input. I guess I'll just give it a shot and if I get noise I'll connect a line driver to see it will help. I will be able to install the PC within a very short distance of the amps...